In order to ensure that data can be trusted, data quality needs to be controlled, and in particular the extent of modifications to raw data needs to be known.
Prior art tools, such as Extract, Transform and Load (ETL) tools, extract data from homogeneous or heterogeneous data sources, and transform the data for storing the data in proper format or structure for querying and analysis purpose and for loading the data into a final target such as a database. Examples of such prior art ETL tools include Ab Initio®, IBM® InfoSphere® DataStage®, Informatica®, Oracle® Data Integrator and SAP® Data Integrator. Such prior art tools try to increase a level of data quality by putting in place controls, such as functional (semantic) controls and technical controls.